TiO2-coated active carbon composites with increased photocatalytic activity prepared by a properly controlled sol-gel method

TiO2-coated active carbon (TiO2/AC) was prepared by a properly controlled sol-gel method with a subsequent heat treatment. Photoactivity of the TiO2/AC composites was performed by the decomposition of Rhodamine B in aqueous solution under UV irradiation. The results indicate that TiO2/AC has a higher efficiency in decomposition of Rhodamine B than pure TiO2 particles as well as the mixture of TiO2 powder and active carbon. It was attributed to three functions of a carrier of active carbon: one, small-nanosize TiO2 particles on composites were not reunited, possible because active carbon suppresses transformation of anatase onto rutile and retards crystallite growth during heat treatment process; two, it increases photocatalytic activity of TiO2 particles by producing high concentration of organic compound near TiO2; three, the carbon in active carbon can make some of TiO2 reduce to Ti(3+)ions that prevent recombination of electron-hole pairs and promote the photodegradation. The composites could be very easily reclaimed, recycled and used repeatedly for Rhodamine B removal with preservation its high photoactivity. (c) 2005 Elsevier B.V. All rights reserved.